Norsonic nor140, Instructional Manual, Page: 10 / 220

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Contents
“Go / NoGo” Quality Control feature ................................................................................................ 96
Digital output lines .............................................................................................................................97
Chapter 20 Noise Generator ............................................................................................................98
General ............................................................................................................................................. 98
Selecting noise type and level ......................................................................................................... 98
Adjustments for reverberation measurement ................................................................................... 99
Standard Set Up ............................................................................................................................... 99
Equalization of noise spectrum ........................................................................................................ 99
Chapter 21 Compensation and correction ...................................................................................100
General ........................................................................................................................................... 100
Use of windscreen .......................................................................................................................... 100
Preamplifier correction ....................................................................................................................101
Random incidence and diffuse sound fields ..................................................................................101
Measurement of low sound levels ...................................................................................................101
Measuring the self-noise ................................................................................................................ 102
Measurement of high sound levels ................................................................................................ 102
Chapter 22 Reverberation time measurements ...........................................................................104
What is reverberation time? ............................................................................................................ 104
Calculating the reverberation time ................................................................................................. 105
Measurement with noise excitation ................................................................................................ 105
Measurement with impulse excitation ............................................................................................ 106
Measurement with swept sine excitation .........................................................................................107
Implementation in Nor140 .............................................................................................................. 108
Excitation signals ............................................................................................................................ 109
Minimum reverberation time possible ............................................................................................ 109
Maximum reverberation times ........................................................................................................ 109
Measuring according to the integrated impulse response method ................................................ 111
Measuring according to interrupted noise method .........................................................................113
Measuring according to interrupted noise method with external noise ..........................................115
Measuring according to the Swept Sine method ............................................................................116